Photoanode with enhanced performance achieved by a novel charge modulation strategy without sacrificial agents

[Display omitted] •Proposes a cost-effective and efficient photochemical modification system, which introducing a BiVO4 seed layer to improve photoelectrochemical (PEC) performance without any cocatalysts or sacrificial agents. And the photocurrent density of BiVO4 seed layer with a thickness of 312 nm was improved by 40% to 0.99 mA cm−2 at 1.23 VRHE.•The BiVO4 seed layer effectively inhibits the recombination of electron-hole pairs and improves the charge transfer efficiency, leading to a “slow” decrease in the current density of the composite photoanode from 32% to 9.8%.•Using the feedback model of the scanning photoelectrochemical microscopy (SPECM) to in-situ quantitatively study the hole transfer kinetics of BiVO4 with different seed layer thicknesses, revealed that photoelectrode with a seed layer thickness of 312 nm have the highest kinetic rate constant (0.62 × 10−2 cm s−1), which is roughly 5 times of the pristine photoelectrode (0.11 × 10−2 cm s−1). Although the catalytic effect can be enhanced by using sacrificial agents, it still faces numerous difficulties in large-scale production applications. Investigating the improvement of photocatalytic efficiency without sacrificial agents is therefore crucial. This study proposes a cost-effective and efficient photochemical modification system that utilizes a seed layer of BiVO4 to improve photoelectrochemical (PEC) performance, the result shows that the photocurrent density of BiVO4 with a seed layer thickness of 312 nm was improved by 40% to 0.99 mA cm−2 at 1.23 VRHE without any sacrificial agent. Meanwhile, Electrochemical impedance spectroscopy (EIS) and intensity modulated photocurrent spectroscopy (IMPS) demonstrated that the introduction of the seed layer effectively prevents the recombination of electron-hole pairs and improves the charge transfer efficiency, leading to a “slow” decrease in the current density of the composite photoanode (from 32% to 9.8%) in combination with the linear sweep voltammetry (LSV) results. We exhibit the scanning photoelectrochemical microscopy (SPECM) method to in-situ quantitatively study the hole transfer kinetics with different seed layer thicknesses using the feedback model and find those photoelectrodes with a thickness of 312 nm has the highest kinetic rate constant of 0.62 × 10−2 cm s−1 which is approximately 5 times higher than that of the pristine photoelectrode (0.11 × 10−2 cm s−1).